مهندسی عمران شریف (Feb 2019)
EVALUATING THE PERFORMANCE OF ZNO NANOPARTICLES ON THE CEMENT BASED MATERIALS ENGINEERING CHARACTERISTICS
Abstract
Nowadays, due to the combustion of fossil fuels and widespread applications of chemical compounds in industries, huge amounts of pollutants are released into the environment. Thus, new technologies, such as nanotechnology, should be employed to solve this problem and degrade the pollutants. Investigations reveal that photocatalytic Oxidation- reduction reaction compared to conventional methods of removing contaminants is more efficient. The aforementioned reactions are activated easily by sunlight. It appears that the use of photocatalytic nano particles as a complementary to the composition of cement- based coatings could decompose a wide range of organic pollutants, which result from fossil fuel combustion and chemical compounds. In this paper, the zinc oxide nanoparticles with different cement replacement levels of 0.1, 0.25, 0.5, 0.75, 1and 2 were used to create cement based surfaces with photocatalytic properties in cement matrix. In order to investigate the photocatalytic properties and the factors affecting the performance in the solution media, the methylene blue solution was used at a concentration of 5 milligrams per liter. The absorption was measured by a spectrophotometer. The results indicate that with increasing the substitution level of nanoparticles in cement paste, the photocatalytic properties were improved and the time of decomposition of methylene blue became shorter. In order to evaluate the performance of ZnO nanoparticles in the mechanical properties and durability of mortars containing the nanoparticles (with percentages 0.1,0.25,0.5,0.75,1and 2), compressive strengths, Rapid Chloride Migration coefficients, permeable voids levels and capillary water absorption contents were measured. The investigation into the mechanical properties and durability of the mortars, containing the nanoparticles, shows that the mixture with 0.75\% nanoparticles outperformed the other mixtures in compressive strength in 28days. By increasing the substitution level of nanoparticles, the discontinuity between capillary spaces was increased and lower pore volumes were obtained, leading to a significant enhancement in the resistance against diffusion of chloride ions into concrete.
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